Pneumatic and hydraulic actuation systems Lecture 4 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 4 7.1: Actuation system Transform output of control system (i.e. µprocessor) into action (controlling) on device / machine Examples are: Electrical output from controller to a linear motion to move a load Electrical output from controller to control amount of liquid passing through a pipe Controller Actuator output input Electrical signal motion 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 3 Types Pneumatic and hydraulic actuator (Chapter 7) Mechanical actuator (Chapter 8) Electrical actuator (Chapter 9) 4/23/2017 SME3252: Mechatronics Lecture 3
7.2: Pneumatic and hydraulic systems Pneumatic signals – to control final control elements The electrical signal – actuate large valve and high power control devices Drawbacks – compressibility of air Hydraulic signals – higher power control devices Drawbacks – expensive, hazards due to oil leaks 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 PSI (lb/in2) Pounds per Square Inch determines amount of force GPM Gallons per Minute determines speed of action 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 PRESSURE = FORCE/AREA Find Pressure, F2: 200 lbf Pressure = 10 psi 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 7.2.1: Hydraulic Actuator Tool or equipment powered by the movement of fluid under pressure. Pressurized hydraulic oil - sump Heavy duty - brakes, jacks & tractor lifts. 4/23/2017 SME3252: Mechatronics Lecture 3
Hydraulic Power Supply Motor Pump Pressure relief valve Non-return valve Accumulator Oil Sump Return 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 Figure 7.1 (a) Hydraulic power supply, (b) accumulator 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 4/23/2017 SME3252: Mechatronics Lecture 3
Parts of a Hydraulic System Pump - pressurize and move fluid from one part of the system to another Valves Ball Check Solenoid / power transfer Relief Filters Remove impurities in oil Heat exchangers Remove heat created by high pressure and moving parts Accumulators 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 Hydraulic Pump 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 Hydraulic pumps are usually one of four types: a. PISTON b. GEAR c. VANE d. INTERNAL ROTOR 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 4 a. Piston Pumps Work well at PSI’s of 2000 or more Single piston pump used in bottle jacks Require several pistons working together to generate enough volume for tractor applications Necessarily involve many moving parts Refer to Figure 7.2c for radial piston pump and 7.2d for axial piston pump 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 4 b. Gear Pumps Work well at 1500 PSI and below Work with a minimum of moving parts Less expensive to manufacture than piston type pumps Disadv. – leakage occurs 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 3 Gear Pump driven gear idler gear 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 c. Vane Pump 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 ACCUMULATORS Dampens hydraulic shock Supply of pressure if pump fails Maintain pressure without continuous pump operation Demand changes Make-up Three types Piston Bladder Direct contact - 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 Figure 7.2 (a) Gear pump, (b) vane pump, (c) radial piston pump, (d) axial piston pump with swash plate 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 4/23/2017 SME3252: Mechatronics Lecture 3
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SME3252: Mechatronics Lecture 3 Application 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 HYDRAULIC SYSTEMS ADVANTAGES Long distances Great flexibility (any shape or form) Variable speed control Reliability DISADVANTAGES Need for positive confinement Oil is flammable High pressure (typically 3000 psi) Need for filtration 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 Pneumatic Actuator Compressed air Light duty Air 6 – 8 bar motion Compressor Air receiver Air regulator Piston, Valve, switching Store compressed air Set pressure 4/23/2017 SME3252: Mechatronics Lecture 3
Pneumatics – Basic Principles Pneumatics – The study of the mechanical properties of air and other gasses. A gas under pressure has the ability to exert a force Pascal’s Law states that a compressed gas will exert pressure equally in all directions A pressure acting over an area will result in a net force being applied 4/23/2017 SME3252: Mechatronics Lecture 3
Pneumatics – Basic Principles 4/23/2017 SME3252: Mechatronics Lecture 3
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Pneumatic Power Supply Motor Compressor Silencer Filter Pressure relief valve Cooler Filter and water trap -dry and dust free Air receiver 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 3 Figure 7.3 Pneumatic power supply 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 4 Compressor To compress air Three types: Piston Screw Diaphragm Air receiver to store compressed air Regulator to regulate the pressure Automatic power cut-off above set pressure Pressure relief valve 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 4 Compressor 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 3 Figure 7.4 (a) Single-acting, single stage, vertical, reciprocating compressor, (b) rotary vane compressor, (c) screw compressor 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 Pneumatic Circuit 4/23/2017 SME3252: Mechatronics Lecture 3
SME3252: Mechatronics Lecture 3 4/23/2017 SME3252: Mechatronics Lecture 3
Application – Robotic System 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 4 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 4 Exercises Power supply components for hydraulic system and pneumatic system – explain with diagram and identify difference Examples of application for both system Advantages and disadvantages of each system 4/23/2017 SME3252: Mechatronics Lecture 4
SME3252: Mechatronics Lecture 4 End of Lecture 4 4/23/2017 SME3252: Mechatronics Lecture 4